This news was sent in by an EDA supporter with a special interest in the consequences of building on floodplains:
Some time ago, I heard the new pumping station for Cranbrook had been cancelled – article in the Exmouth Journal re flooding at Clyst St Mary confirms this…
“Adding to residents’ fears, they have been told by the Environment Agency that South West Water has cancelled plans for a new sewage treatment works for the Cranbrook development, instead sending sewage from the new town to a pumping station at Blue Ball Lane.”
Sidmouth Independent News 
My brother had a similar problem of sewage in a side pipe, which serves about 20 houses, backing up because of the load from a new housing development on the main pipe. He managed to persuade his local water company (Southern Water I think) to install a non-return valve in their side pipe. Problem solved.